1. Field of the Invention
This invention relates generally to drill bits for providing holes in earth formations for wells, blast holes and the like. It is more particularly directed to rotary drill bits for use in relatively hard earth formations which may also be abrasive in nature, such as taconite or the like. One of the problems associated with drill bits of the class of drilling activities in which my invention finds substantial advantageous use, is concerned with economics, not only in the cost of labor for running drilling equipment, but in the cost of the drilling equipment itself, including the expendable drilling bits. My invention provides an improved economic advantage, when considering the factors set forth above, and others, in that it provides a substantially longer life, may be easier to fabricate of available components and is reliable in operation.
2. Description of the Prior Art
The following is a list of prior art patents noted in the course of an investigation concerning the subject matter of this application;
______________________________________ U.S. Pat. No. Inventor Date of Issue ______________________________________ 3,193,028 Radzimovsky 7/6/65 3,251,634 Dareing 5/17/66 3,344,870 Morris 10/3/67 3,461,983 Hudson et al 8/19/69 3,572,452 Winberg 3/30/71 3,628,616 Neilson 12/21/71 3,866,695 Jackson 2/18/75 3,921,735 Dysart 11/25/75 3,952,815 Dysart 4/27/76 2,126,035 Reed 8/9/38 2,126,040 Reed 8/9/38 2,177,333 Reed 10/24/39 2,673,128 Reed 3/23/54 2,664,322 Boice 12/29/53 2,690,935 Alexander 10/5/54 2,719,026 Boice 9/27/55 4,013,325 Rear 3/22/77 4,140,189 Garner 2/20/79 4,183,417 Levefelt 1/15/80 ______________________________________
While the above prior art is set forth to disclose the information available to the inventor as a result of a preliminary investigation, it is not believed that any one of the patents listed is more relevant than any of the others and therefore no other comments are believed necessary.